Expectations:
1. Climate and soil characteristics will explain most of the patterns in MAOM content and stability, and these controls vary by site and over large spatial scales.
- Warmer sites and sites with more clay and iron oxides will have greater concentrations of MAOM.
- MAOM turnover will be more strongly controlled by mineralogy, with more clay-rich and iron-rich sites having the oldest and most stable MAOM.
Counterpoint: Warmer sites should also have smaller standing nutrient pools, which may lead to more root exudation from trees, or mining by associated fungi, as a way to liberate nutrients from MAOM. This may result in smaller, more dynamic MAOM stocks with relatively short turnover times.
2. Within-site patterns in tree mycorrhizal association will explain a smaller but still important amount of variation in MAOM content and turnover time.
- ECM-dominated plots will have less MAOM than AM-dominated plots
- ECM-dominated plots will have shorter MAOM turnover times than AM-dominated plots (because ECM taxa may be able to liberate mineral-bound SOM)
Site Characteristics
| LENO |
18.1 |
1386 |
American Sweetgum, American Hornbeam, Possumhaw |
44.7 +- 13.8 |
1.0 +- 0.4 |
| DELA |
17.6 |
1372 |
Water oak, Red maple, Sugarberry |
37.0 +- 6.3 |
0.88 +- 0.2 |
| ORNL |
14.4 |
1340 |
Red maple, Sour gum, Chestnut oak |
22.0 +- 12.7 |
0.13 +- 0.05 |
| SERC |
13.6 |
1075 |
Tulip poplar, American Beech, American Sweetgum |
17.4 +- 6.2 |
0.27 +- 0.1 |
| HARV |
7.4 |
1199 |
Eastern Hemlock, Northern Red Oak, American Beech |
5.5 +- 1.9 |
0.38 +- 0.1 |
| BART |
6.2 |
1325 |
American Beech, Eastern Hemlock, Red maple |
3.6 +- 0.7 |
0.76 +- 0.5 |
| TREE |
4.8 |
797 |
Sugar maple, Red maple, Gray alder |
5.4 +- 1.1 |
0.34 +- 0.09 |
|
|
proportion.C_HF
|
mg.C.per.g.soil_HF
|
|
Predictors
|
Estimates
|
std. Error
|
std. Beta
|
standardized std. Error
|
p
|
std. p
|
Estimates
|
std. Error
|
std. Beta
|
standardized std. Error
|
p
|
std. p
|
|
(Intercept)
|
0.881
|
0.061
|
0.023
|
0.137
|
<0.001
|
0.864
|
32.631
|
8.890
|
0.009
|
0.238
|
<0.001
|
0.971
|
|
E
|
-0.254
|
0.093
|
-0.410
|
0.126
|
0.006
|
0.001
|
-7.715
|
9.516
|
-0.019
|
0.108
|
0.418
|
0.861
|
|
CDI
|
-1.833
|
1.621
|
0.069
|
0.157
|
0.258
|
0.659
|
-653.508
|
242.244
|
-0.638
|
0.251
|
0.007
|
0.011
|
|
FeOx
|
0.071
|
0.029
|
0.383
|
0.154
|
0.013
|
0.013
|
12.467
|
3.524
|
0.556
|
0.157
|
<0.001
|
<0.001
|
|
E * CDI
|
4.585
|
2.572
|
0.212
|
0.119
|
0.075
|
0.075
|
208.762
|
266.007
|
0.080
|
0.102
|
0.433
|
0.433
|
|
Random Effects
|
|
σ2
|
0.004
|
37.966
|
|
τ00
|
0.000 Site
|
28.290 Site
|
|
ICC
|
0.045
|
0.427
|
|
N
|
7 Site
|
7 Site
|
|
Observations
|
46
|
46
|
|
Marginal R2 / Conditional R2
|
0.362 / 0.391
|
0.348 / 0.627
|
|
|
proportion.N_HF
|
mg.N.per.g.soil_HF
|
|
Predictors
|
Estimates
|
std. Error
|
std. Beta
|
standardized std. Error
|
p
|
std. p
|
Estimates
|
std. Error
|
std. Beta
|
standardized std. Error
|
p
|
std. p
|
|
(Intercept)
|
0.884
|
0.044
|
0.028
|
0.115
|
<0.001
|
0.805
|
1.652
|
0.432
|
0.025
|
0.181
|
<0.001
|
0.892
|
|
E
|
-0.196
|
0.070
|
-0.239
|
0.119
|
0.005
|
0.045
|
-1.140
|
0.544
|
-0.022
|
0.106
|
0.036
|
0.834
|
|
CDI
|
0.601
|
1.183
|
0.493
|
0.134
|
0.612
|
<0.001
|
-28.027
|
11.681
|
-0.237
|
0.196
|
0.016
|
0.227
|
|
FeOx
|
0.014
|
0.021
|
0.092
|
0.138
|
0.503
|
0.503
|
1.000
|
0.193
|
0.771
|
0.149
|
<0.001
|
<0.001
|
|
E * CDI
|
4.381
|
1.946
|
0.252
|
0.112
|
0.024
|
0.024
|
32.087
|
15.169
|
0.213
|
0.101
|
0.034
|
0.034
|
|
Random Effects
|
|
σ2
|
0.002
|
0.127
|
|
τ00
|
0.000 Site
|
0.046 Site
|
|
ICC
|
|
0.269
|
|
N
|
7 Site
|
7 Site
|
|
Observations
|
46
|
46
|
|
Marginal R2 / Conditional R2
|
0.430 / NA
|
0.502 / 0.635
|

|
|
proportion.C_OLF
|
mg.C.per.g.soil_OLF
|
|
Predictors
|
Estimates
|
std. Error
|
std. Beta
|
standardized std. Error
|
p
|
std. p
|
Estimates
|
std. Error
|
std. Beta
|
standardized std. Error
|
p
|
std. p
|
|
(Intercept)
|
0.012
|
0.042
|
-0.024
|
0.171
|
0.766
|
0.887
|
1.786
|
1.709
|
-0.016
|
0.170
|
0.296
|
0.926
|
|
E
|
0.148
|
0.062
|
0.339
|
0.144
|
0.018
|
0.018
|
4.496
|
2.451
|
0.247
|
0.131
|
0.067
|
0.059
|
|
CDI
|
1.768
|
1.125
|
0.066
|
0.193
|
0.116
|
0.732
|
-37.926
|
45.900
|
-0.454
|
0.190
|
0.409
|
0.017
|
|
FeOx
|
-0.009
|
0.020
|
-0.081
|
0.182
|
0.656
|
0.656
|
1.485
|
0.810
|
0.313
|
0.171
|
0.067
|
0.067
|
|
E * CDI
|
-2.933
|
1.731
|
-0.230
|
0.135
|
0.090
|
0.090
|
-87.733
|
68.221
|
-0.159
|
0.124
|
0.198
|
0.198
|
|
Random Effects
|
|
σ2
|
0.002
|
2.663
|
|
τ00
|
0.000 Site
|
0.371 Site
|
|
ICC
|
0.082
|
0.122
|
|
N
|
7 Site
|
7 Site
|
|
Observations
|
46
|
46
|
|
Marginal R2 / Conditional R2
|
0.158 / 0.227
|
0.267 / 0.357
|
|
|
proportion.N_OLF
|
mg.N.per.g.soil_OLF
|
|
Predictors
|
Estimates
|
std. Error
|
std. Beta
|
standardized std. Error
|
p
|
std. p
|
Estimates
|
std. Error
|
std. Beta
|
standardized std. Error
|
p
|
std. p
|
|
(Intercept)
|
0.029
|
0.026
|
-0.032
|
0.132
|
0.263
|
0.808
|
0.091
|
0.055
|
-0.008
|
0.185
|
0.101
|
0.964
|
|
E
|
0.107
|
0.041
|
0.203
|
0.137
|
0.010
|
0.140
|
0.080
|
0.078
|
0.136
|
0.135
|
0.302
|
0.314
|
|
CDI
|
0.155
|
0.699
|
-0.388
|
0.154
|
0.824
|
0.012
|
-1.835
|
1.489
|
-0.475
|
0.205
|
0.218
|
0.021
|
|
FeOx
|
0.006
|
0.012
|
0.075
|
0.158
|
0.635
|
0.635
|
0.048
|
0.026
|
0.326
|
0.179
|
0.069
|
0.069
|
|
E * CDI
|
-2.550
|
1.150
|
-0.286
|
0.129
|
0.027
|
0.027
|
-1.604
|
2.163
|
-0.095
|
0.128
|
0.458
|
0.458
|
|
Random Effects
|
|
σ2
|
0.001
|
0.003
|
|
τ00
|
0.000 Site
|
0.000 Site
|
|
ICC
|
|
0.149
|
|
N
|
7 Site
|
7 Site
|
|
Observations
|
46
|
46
|
|
Marginal R2 / Conditional R2
|
0.255 / NA
|
0.213 / 0.330
|
|
|
proportion.C_FLF
|
mg.C.per.g.soil_FLF
|
|
Predictors
|
Estimates
|
std. Error
|
std. Beta
|
standardized std. Error
|
p
|
std. p
|
Estimates
|
std. Error
|
std. Beta
|
standardized std. Error
|
p
|
std. p
|
|
(Intercept)
|
0.108
|
0.045
|
-0.012
|
0.130
|
0.017
|
0.926
|
3.827
|
1.849
|
-0.014
|
0.209
|
0.039
|
0.945
|
|
E
|
0.106
|
0.071
|
0.264
|
0.130
|
0.136
|
0.042
|
2.613
|
2.318
|
0.180
|
0.122
|
0.260
|
0.141
|
|
CDI
|
0.039
|
1.208
|
-0.157
|
0.150
|
0.974
|
0.296
|
-66.957
|
50.028
|
-0.486
|
0.226
|
0.181
|
0.032
|
|
FeOx
|
-0.061
|
0.021
|
-0.437
|
0.152
|
0.004
|
0.004
|
0.030
|
0.824
|
0.006
|
0.171
|
0.971
|
0.971
|
|
E * CDI
|
-1.726
|
1.965
|
-0.107
|
0.122
|
0.380
|
0.380
|
-44.265
|
64.686
|
-0.079
|
0.116
|
0.494
|
0.494
|
|
Random Effects
|
|
σ2
|
0.002
|
2.299
|
|
τ00
|
0.000 Site
|
0.863 Site
|
|
ICC
|
0.014
|
0.273
|
|
N
|
7 Site
|
7 Site
|
|
Observations
|
46
|
46
|
|
Marginal R2 / Conditional R2
|
0.335 / 0.344
|
0.269 / 0.469
|
|
|
proportion.N_FLF
|
mg.N.per.g.soil_FLF
|
|
Predictors
|
Estimates
|
std. Error
|
std. Beta
|
standardized std. Error
|
p
|
std. p
|
Estimates
|
std. Error
|
std. Beta
|
standardized std. Error
|
p
|
std. p
|
|
(Intercept)
|
0.086
|
0.034
|
-0.017
|
0.124
|
0.011
|
0.893
|
0.148
|
0.064
|
-0.013
|
0.208
|
0.022
|
0.951
|
|
E
|
0.088
|
0.054
|
0.191
|
0.129
|
0.100
|
0.139
|
0.066
|
0.083
|
0.112
|
0.128
|
0.430
|
0.383
|
|
CDI
|
-0.756
|
0.905
|
-0.416
|
0.145
|
0.404
|
0.004
|
-2.470
|
1.739
|
-0.491
|
0.226
|
0.155
|
0.030
|
|
FeOx
|
-0.020
|
0.016
|
-0.185
|
0.149
|
0.214
|
0.214
|
0.008
|
0.029
|
0.046
|
0.177
|
0.794
|
0.794
|
|
E * CDI
|
-1.831
|
1.489
|
-0.149
|
0.121
|
0.219
|
0.219
|
-1.233
|
2.317
|
-0.064
|
0.121
|
0.595
|
0.595
|
|
Random Effects
|
|
σ2
|
0.001
|
0.003
|
|
τ00
|
0.000 Site
|
0.001 Site
|
|
ICC
|
|
0.242
|
|
N
|
7 Site
|
7 Site
|
|
Observations
|
46
|
46
|
|
Marginal R2 / Conditional R2
|
0.339 / NA
|
0.231 / 0.417
|
ggarrange(propC.myc.flf, propC.myc.olf, propC.myc, nrow=1, ncol=3, common.legend=T, legend="right", labels=c("a", "b","c"))
## `geom_smooth()` using formula 'y ~ x'
## `geom_smooth()` using formula 'y ~ x'
## `geom_smooth()` using formula 'y ~ x'
## `geom_smooth()` using formula 'y ~ x'

ggsave("som.proportion.plots.tiff",path="figures/", width= 30, height= 10, units="cm")
concC.fe.hf=ggplot(final_data, aes(x=FeOx, y=mg.C.per.g.soil_HF, color=Site))+
geom_smooth(method="lm",size=2, se=F)+
geom_point()+
labs(x=" % FeOx ", y="[MAOM C] (mg/g soil)", colour="Site")+
theme_cowplot()+
theme(legend.title=element_text(hjust=0.5, size=16), legend.text=element_text(size=15), axis.text=element_text(size=15), axis.title=element_text(size=19))
concN.fe.hf=ggplot(final_data, aes(x=FeOx, y=mg.N.per.g.soil_HF, color=Site))+
geom_smooth(method="lm",size=2, se=F)+
geom_point()+
labs(x=" % FeOx ", y="[MAOM N] (mg/g soil)", colour="Site")+
theme_cowplot()+
theme(legend.title=element_text(hjust=0.5, size=16), legend.text=element_text(size=15), axis.text=element_text(size=15), axis.title=element_text(size=19))
ggarrange(concC.fe.hf, concN.fe.hf, nrow=2, ncol=1, common.legend=T, legend="right", labels=c("a", "b"))
## `geom_smooth()` using formula 'y ~ x'
## `geom_smooth()` using formula 'y ~ x'
## `geom_smooth()` using formula 'y ~ x'

ggsave("hf.conc.fe.tiff",path="figures/", width= 14, height= 20, units="cm")
|
|
C.N_FLF
|
C.N_OLF
|
C.N_HF
|
|
Predictors
|
Estimates
|
std. Error
|
std. Beta
|
standardized std. Error
|
p
|
std. p
|
Estimates
|
std. Error
|
std. Beta
|
standardized std. Error
|
p
|
std. p
|
Estimates
|
std. Error
|
std. Beta
|
standardized std. Error
|
p
|
std. p
|
|
(Intercept)
|
22.908
|
5.411
|
-0.001
|
0.172
|
<0.001
|
0.998
|
20.352
|
7.346
|
-0.005
|
0.201
|
0.006
|
0.982
|
20.317
|
2.785
|
-0.017
|
0.149
|
<0.001
|
0.908
|
|
E
|
9.057
|
7.804
|
0.420
|
0.134
|
0.246
|
0.002
|
15.486
|
9.709
|
0.506
|
0.130
|
0.111
|
<0.001
|
7.802
|
3.389
|
0.170
|
0.082
|
0.021
|
0.040
|
|
CDI
|
81.259
|
145.316
|
0.111
|
0.192
|
0.576
|
0.562
|
186.418
|
198.175
|
0.187
|
0.219
|
0.347
|
0.393
|
-229.967
|
75.440
|
-0.783
|
0.160
|
0.002
|
<0.001
|
|
FeOx
|
-6.095
|
2.569
|
-0.412
|
0.174
|
0.018
|
0.018
|
-3.414
|
3.374
|
-0.179
|
0.177
|
0.312
|
0.312
|
0.659
|
1.216
|
0.063
|
0.117
|
0.588
|
0.588
|
|
E * CDI
|
-35.993
|
217.148
|
-0.021
|
0.126
|
0.868
|
0.868
|
-98.413
|
270.697
|
-0.045
|
0.123
|
0.716
|
0.716
|
-162.162
|
94.601
|
-0.134
|
0.078
|
0.086
|
0.086
|
|
Random Effects
|
|
σ2
|
27.040
|
40.775
|
4.890
|
|
τ00
|
3.555 Site
|
11.218 Site
|
2.132 Site
|
|
ICC
|
0.116
|
0.216
|
0.304
|
|
N
|
7 Site
|
7 Site
|
7 Site
|
|
Observations
|
46
|
46
|
46
|
|
Marginal R2 / Conditional R2
|
0.243 / 0.331
|
0.230 / 0.396
|
0.633 / 0.745
|
|
|
mg.C.per.g.soil_HF
|
mg.N.per.g.soil_HF
|
|
Predictors
|
Estimates
|
std. Error
|
std. Beta
|
standardized std. Error
|
p
|
Estimates
|
std. Error
|
std. Beta
|
standardized std. Error
|
p
|
|
(Intercept)
|
15.302
|
3.428
|
0.011
|
0.281
|
<0.001
|
1.228
|
0.185
|
0.002
|
0.204
|
<0.001
|
|
plotBA
|
0.562
|
1.179
|
0.062
|
0.130
|
0.634
|
-0.027
|
0.079
|
-0.052
|
0.151
|
0.733
|
|
Random Effects
|
|
σ2
|
52.173
|
0.257
|
|
τ00
|
39.699 Site
|
0.045 Site
|
|
ICC
|
0.432
|
0.148
|
|
N
|
7 Site
|
7 Site
|
|
Observations
|
46
|
46
|
|
Marginal R2 / Conditional R2
|
0.004 / 0.434
|
0.003 / 0.150
|